JB

An interesting article in the New York Times last Friday finds polarization in book buying habits-- one group of people (presumably liberals) purchase mostly liberal books on politics while another group (presumably conservatives) purchase and read mostly conservative books on politics. So far so good. This seems to square with the literature that says that people tend to seek out information they already agree with.

The Times then makes a puzzling assertion:

This finding appears to buttress the argument made by Cass Sunstein, a law professor at the University of Chicago, in his influential study "Republic.com" (Princeton University Press, 2001) that contemporary media and the Internet have abetted a culture of polarization, in which people primarily seek out points of view to which they already subscribe.

Hardly. Sunstein's book made the controversial claim that the Internet was a special cause of political polarization. But the polarization described in the article concerns the most traditional of mass media, i.e., books. Using the Internet (in particular, Amazon.com) made it easier for researchers to *discover* this polarization. That's not the same thing as saying that the Internet *caused* the polarization that led to the book buying habits measured in the study.

The argument that best supports Sunstein's claim in Republic.com would be that people used the Internet to find books of a similar character, and that most people now buy political books on the Internet rather than in bookstores, thus causing the enhanced political polarization. If people already tended to buy books of a similar political character in traditional bookstores and were easily able to find like-minded books there, the Internet's filtering technologies would not be a major cause of the enhanced polarization, although they might be an additional cause at the margins.

The best way of testing whether the Internet contributed to the polarization would be to determine who purchased liberal and conservative books in 1992 or earlier, before the Internet became a prominent feature of American political discourse. (Note, ironically, that it will be more difficult to do that precisely because the Internet was not as widely used at that point.). And even then it's not clear that the Internet itself would be the cause; it could be other features of American political life that have been changing in the past twenty years. More research needs to be done to prove that the Internet exacerbates political polarization.

My guess is that the Internet makes polarization more salient, and also, as we have seen, easier to measure by social scientists. But that is not the same thing as saying, as has been suggested, that Internet speech presents special harms to democracy.

Obviously, the New York Times has an interest in reporting stories that make the traditional mass media look good and the Internet look bad as a source of people's political information. (And they have done a few of these stories in recent memory). But we have to look further if we want to get to the truth of the matter.